Sustainability of wildlife harvests is critical but difficult to assess. Evaluations of sustainabilitytypically combine modelling with the measurement of underlying abundances. For manytaxa harvested in developing countries, however, abundances are near-impossible to surveyand a lack of detailed ecological information impedes the reliability of models. In suchcases, repeated surveys of the attributes of harvested individuals may provide more robustinformation on sustainability. If the numbers, sizes and other demographic attributes of animalstaken for the commercial trade do not change over biologically significant time intervals(decades), there is a prima facie case that the harvest is indeed sustainable. Here, wereport the results of examinations of > 4,200 reticulated pythons (Python reticulatus) takenfor the commercial leather industry in northern and southern Sumatra, Indonesia. The numbers,mean body sizes, clutch sizes, sizes at maturity and proportion of giant specimenshave not decreased between our first surveys (1995) and repeat surveys (2015). Thus,despite assumptions to the contrary, the harvest appears to be sustainable. We use ourdata to inform the design of future monitoring programs for this species. Our study underpinsthe need for robust science to inform wildlife trade policy and decision-making, andurges wildlife managers to assess sustainability of difficult-to-survey terrestrial wildlife bydrawing inferences directly from the harvest itself.

To a broader readership - the same basic principles apply here, as in managing most wildlife - we DO NOT NEED TO KNOW how many there are. We just make inference about the ones we don't see (the uncaptured ones) from the ones we do see. If the ones we catch stay the same (in age, size, gender, catch per unit effort, etc etc), we infer the ones we don't catch are also still the same. This is the foundation of state and interstate management plans for bears, mountain lions, sea turtles, tuna, shrimp, etc etc etc. Which - if followed and enforced - virtually always work.

It continues to amaze me that some people insist that herps are different from other wildlife. Does anybody really think it's easier to count tuna or mountain lions, than it is to count snakes? They all hide or run away. Almost everything out there is an unholy bitch to count - which is one reason professionals don't emphasize the estimation of abundance. Another is, abundance is a trailing indicator - it comes after changes in survival, fecundity, migration, occupancy etc. Professionals tend to be more interested in measuring those things, and generally only develop abundance estimates when nonprofessionals force us to. Abundance is nearly always an expensive hassle to estimate, and it's rarely worth the effort. Getting that answer just winds up prompting the question that should have been pursued in the first place - why is the abundance what it is? What is driving the changes we see?

BrianThanks for calling attention to this interesting report. Although much of it is above my intellectual capacity, nevertheless, the gist of the report is very informative.

Jimi,Years ago I once looked into the harvest of bears and cougars in Utah. I recall the agency or Commission kept increasing the number of cougars that could be harvested annually. It seemed to me they had some idea of the overall population of those species at that time. Can you fill me in with some sort of update on the harvesting of cougars (and bears) in Utah in relation to the estimated populations of those species?

Perhaps I am mistaken that the agency had some estimates of the over all bear and cougar populations. But I do recall seeing yearly harvest data at that time.

It continues to amaze me that some people insist that herps are different from other wildlife. Does anybody really think it's easier to count tuna or mountain lions, than it is to count snakes? They all hide or run away. Almost everything out there is an unholy bitch to count - which is one reason professionals don't emphasize the estimation of abundance. Another is, abundance is a trailing indicator - it comes after changes in survival, fecundity, migration, occupancy etc. Professionals tend to be more interested in measuring those things, and generally only develop abundance estimates when nonprofessionals force us to. Abundance is nearly always an expensive hassle to estimate, and it's rarely worth the effort. Getting that answer just winds up prompting the question that should have been pursued in the first place - why is the abundance what it is? What is driving the changes we see?

I dont want to go off topic into other subjects explored on this and other reptile focused forums but Im glad you said this, an overspecialization in interests, leads to a lack of connectivity in understanding of principles that are shared by many, almost all, even, animals. Even many seemingly "elite" behaviors can have their versions across taxa.

But thats enough of my digressing. I learn more inside stuff from you Jimi, about so much. Thanks.

Despite two decades of harvesting since our first survey, attributes of the commercial harvest of reticulated pythons were strikingly similar. Over the past 20 years, nearly one million reticulated pythons have been removed from the wild in the two provinces where our study facilities are located; but nonetheless, the numbers, sizes and fecundities of the animals harvested have not declined.

Our findings accord with harvests of other large tropical reptiles. Argentine Tegu lizards (Tupinambis) and Yellow Anacondas (Eunectes notaeus) also appear to be sustaining large annual harvests.

we should also expect to see the proportion of truly giant snakes in our samples (those larger than 450 cm SVL) decrease over time. Our results do not support this conclusion, and show that giant snakes are equally common between survey periods

Thus, despite assumptions to the contrary, the harvest appears to be sustainable.

Yet another study that supports everything I've said about snake ecology and wild harvest. Its tough to count anything but if you understand snake ecology, Yes it is much harder to count snakes then bears or mountain lions. You can almost never count more then a small fraction of any snake population. The guys in the snake skin trade (I'm not a fan) have been coming under heavy attack from various US based groups but its the guys catching the snakes that are and have been telling the truth.

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hunters are encouraged to kill Burmese Pythons (Python molurus) in an attempt to control snake numbersthis kind of limited culling will likely have no effect on invasive populations of Burmese Pythons

This video ties in perfectly with this study and illustrates how lies, activist groups and the propaganda of junk science all go together and result in ineffective bans that do nothing for conservation or wildlife protection but do harm innocent people. With well over 600.000 views its clear this one propaganda piece alone has mislead a lot of people. The takeaways are the lie filled narrative thru out and the truthful evaluation of the python's biology and abundance by the skin trader at about the 15 minute mark. Like it or not the skin trade in python's is a viable and sustainable industry that utilizes a natural resource and provides opportunity's for people who would otherwise have none.

Interesting that this thread started with the posting of a science article - from one of the very most respected and prolific academic-herpetology labs in the world, the Shine lab - stating that the retic skin trade, on Sumatra, anyway, is sustainable based on the scientific evidence created over the last 20 years.

I feel the need to repeat this:

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2) If wildlife agencies - who always partner extensively with academia, i.e. "the guys best-equipped to establish objective reality" - can't come up with a reasonable, credible scientific ("can a harvest be sustained, demographically speaking?") basis for maintaining excessively restrictive harvest limits - how could CBD or other "environmental" litigants? Emphasis on "can".

3) If you're talking about animal-welfare or philosophical perspectives ("should a harvest be allowed?") then you're talking about a whole different thing. The folks in this category are not environmental organizations in the classical sense. Emphasis on "should". Big difference between can and should.

Can the Sumatran retic-skin trade be done sustainably? Science says "yes, it can". Animal-welfare organizations don't like this "yes" answer. But really, they are concerned with "should", not about "can". They aren't scientists or managers, they are animal-welfare organizations.

Managers - and the politicians who govern them - are left to make a call. Politicians have to balance the cans and the shoulds in life. I don't know what the Malaysian authorities have decided to do with their retic wildlife resource; I believe their system of government is more or less democratic. Regardless, people are people - some folks want this, some folks want that, and there are winners and losers in life. Democracy, autocracy, kleptocracy, oligarchy, it doesn't matter which - there's always different people competing for their wants and needs and wishes. Some of them lie. Life is suffering. Yearning for liars to stop lying is a source of suffering. Yearning for an end to the use (lethal or not) of animals to satisfy human needs and wants is a source of suffering. One could try instead to simply live right, say right, and think right, according to one's own moral compass.

Yearn less for foolish things, and one will suffer less, and also cause less suffering to others.

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if you understand snake ecology, Yes it is much harder to count snakes then bears or mountain lions. You can almost never count more then a small fraction of any snake population.

The bit about "small fraction" applies to virtually any wildlife population, unless you're talking about some insanely high-intensity program like the Mexican wolf or California condor recovery programs, which have most or all the free-ranging individuals radio-tagged. No, snakes are not harder to count than bears or mountain lions. All are hard, but people can get good at it, and develop reliable techniques to study them.

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